Friends say Brian and Beverly Mauck were “the great American couple” — newlyweds with a fondness for friends, family and scuba diving.

Those who knew the couple aren’t the only ones struggling with their slaying last weekend, allegedly at the hands of a neighbor who had recently been released from prison for killing his mother 16 years ago. Police also spent Monday trying to determine why the Maucks were shot to death in their rural home in Graham, Pierce County.

“There will never be a motive. There is no reason behind it,” said Pierce County sheriff’s spokesman Ed Troyer. “The guy was in prison 15 years; if you looked at him the wrong way, he’d probably kill you.”

Brian Mauck, 30, and his wife Beverly, 28, were found Saturday by a neighbor who noticed that the front door of their home had been kicked in, Troyer said. He said investigators are still looking into whether the Maucks were robbed.

Daniel Tavares Jr., 41, was booked into the Pierce County Jail early Monday on investigation of two counts of aggravated first-degree murder.

His wife, Jennifer Tavares, 37, is also being held for investigation of rendering criminal assistance and making false statements. Troyer said she lied to investigators to cover for her husband.

Investigators believe the Maucks knew Tavares and his wife — the two couples lived about four doors from one another. But, Troyer adds, the couples did not appear to be friends.

Tavares was released from a Boston-area maximum-security prison in June after serving 16 years for manslaughter in the slaying of his mother with a carving knife. He was supposed to be released to the Florida Department of Corrections for an outstanding charge, but instead he wound up in Graham with a wife whom he met through a prison pen-pals Web site.

Brian Mauck worked at Emerald Aire, an air-conditioning company in Auburn. Beverly Mauck worked at a car dealership.

Doug Happe, president of Emerald Aire, described Brian Mauck as hard-working and willing to help anyone. On Friday, Mauck, an employee of eight years, helped the company’s receptionist carry in the company Christmas tree.

The Maucks honeymooned in the Turks and Caicos Islands and spent much of their time scuba diving.

“They are an amazing couple. They had the two greatest smiles,” said Happe, who called the Maucks “the great American couple.”

Beverly Mauck and her family moved to the area when she was 9, said her father, Darrel Slater, of Lynnwood. He said his daughter’s relationship with Brian Mauck began as a “teenage thing.”

“I know … they were really great kids and everything else. It’s really sad that somebody just got out of prison and took their lives before they even got started,” Slater said.

Tavares’ father, Daniel Tavares Sr., described his son as a cocaine addict who had threatened to kill him.

Speaking by phone from his home in Zephyrhills, Fla., Tavares, 63, said that he last saw his son nearly 20 years ago when he helped get him into a drug-rehabilitation center northeast of Tampa. But the rehab stint was short-lived because his son was caught using drugs and stealing, his father said.

Since September 1990, the younger Tavares has been wanted by the Pasco County, Fla., Sheriff’s Office for investigation of contempt of court, according to the Florida Department of Law Enforcement.

But after getting kicked out of rehab, the younger Tavares returned home to Massachusetts and in July 1991 killed his mother, Ann Tavares, 46. A man living in a nearby apartment was hurt after trying to intervene.

While in prison for manslaughter, Tavares mailed his father death threats, the elder Tavares said. He said the threats stopped after he complained to the Massachusetts Department of Corrections.

“I don’t know where all the hate is from,” he said.

According to an April 2004 article in The Boston Globe about the state’s toughest prison, Massachusetts Correctional Institution — Cedar Junction, the younger Tavares told a reporter he had spent much of his sentence in solitary confinement.

He was described as someone who seemed to struggle to contain his anger. The younger Tavares told The Globe he was a difficult prisoner but claimed it was as a result of abuse he suffered at the hands of corrections officers.

A spokeswoman for the Massachusetts Department of Corrections declined to say whether he is on probation. A spokeswoman for the Washington state Department of Corrections said he is not being monitored by corrections staff here.

While in prison in Walpole, Mass., Tavares managed to contact someone through INMATE Classified, an Internet prison pen-pal service. In his posting, Tavares described himself as “a 6′, 235 pound Albino gorilla with over 40 real nice tattoos.” He said he loved to “write poetry, play guitar, sing, draw and work out like a bull since I am a Taurus.” He added that he was looking for “love from a lonely female.”

Troyer said the younger Tavares met his wife through the ad. Tavares’ father said he didn’t know his son’s wife, but said that a woman called his house Friday and told him that “Daniel is out of prison and is on his way down there to take care of you.” He said he didn’t recognize the woman’s voice.

The elder Tavares said he spent the weekend terrified that he and his wife would be slain.

After hearing that his son had been arrested in connection with the slayings of the Maucks, Tavares said he had mixed emotions.

“It’s grief and relief at the same time,” he said. “Grief that it was those poor people and relief that it wasn’t me.”

Seattle Times staff reporter Brian Alexander and news researcher Miyoko Wolf contributed to this report. Information from The Associated Press is included in this report.